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9 Comments
wglb
Paper in Science: https://www.science.org/doi/10.1126/science.adt6666
zelon88
[flagged]
Gualdrapo
I wish someone like Columbus/Reynolds/Tange could catch on this. It'd be awesome a road bike made of fancy/extra durable stainless steel tubing, lugged, horizontal top tube and that classic geometry but with disc brakes and thru axles.
ajuc
Some medieval swords were made in a similar way (twisting and re-flattening the billet many times).
accrual
Pretty fascinating work. My layman understanding is they twist the steel in certain ways to create microscopic structures or patterns in the steel that then resist later deformation.
It sounds kind of like the ripstop lines sown into X-Pac materials – when a rip or flaw occurs, its (ideally) bounded by the structures sown into the material.
hinkley
I sometimes watch machinists and blacksmiths on youtube.
One of the things I've become more aware of lately is the fact that hardened steel eats through cutting tools like candy, so the solution is to anneal the steel, do most of the shaping, harden it again (temper it for as much as 24 hours in a very smart oven that slowly slowly drops the temps), and then finish the piece with sanding and grinding tools instead of cutting tools.
I wonder if this treatment survives annealing and hardening cycles or if that just destroys the structure.
kazinator
> In testing the metal after treatment, the research team found it boosted its strength by a factor of 2.6 while also cutting strain due to ratcheting by two to four orders of magnitude compared to untreated stainless steel. Such improvements, the team claims, could allow products made using the metal to be up to 10,000 times more resistant to fatigue.
LOL; that second sentence mainly just explains that four orders of magnitude means 10,000.
MisterTea
> The new technique involved repeatedly twisting a sample of 304 austenitic stainless steel in a machine in certain ways. This led to spatially grading the cells that made up the metal, resulting in the build-up of what the team describes as a submicron-scale, three-dimensional, anti-crash wall.
Interesting. Not a metallurgist but this takes advantage of stainless steels natural tendency to work harden. e.g. if you have ever broken a paperclip or other piece of steel by bending it back and forth until it fatigues, fractures, and beaks off. That happens in soft standard steels like A36 (edit forgot to finish this…) However, in stainless steel instead of a fracture forming at the bends crease, it hardens. As you try to bend it again, it bends in a new place as the original crease has hardened.
> Such improvements, the team claims, could allow products made using the metal to be up to 10,000 times more resistant to fatigue.
Very bold claim that if true is a game changer. My concern is how does this process scale to large complex structural pieces? Assuming since this internal structure will be ruined by annealing it must be performed after final shaping of the material. Welding should not be effected, especially low heat effect zone processes like laser and electron beam as you account for material alteration from welding during design.
ggm
I think this is discussed in "the new science of strong materials" by J.E. Gordon, (1968) alongside why some aluminium alloys get stronger if you "age" them before use.